A 1945 photo shows the unveiling of the Mona Lisa after it was returned to the Louvre from a safehouse in the French countryside.

By Jenny Barchfield, Associated Press Writer

PARIS  On the eve of World War II, curators at the Louvre swathed the museum's most priceless painting — the Mona Lisa— in layers of waterproof paper, boxed it up and spirited it to the French countryside for safekeeping. Leonardo da Vinci's smiling maiden moved another five times during the war before she was brought, safe and sound, back to the Louvre.

Mona Lisa wasn't alone.

A new Louvre exhibition opening Thursday brings together photos of the museum before, during and after the war, recording how thousands of pieces of art were taken to safehouses far from the fighting.

Black-and-white shots from 1939 show workers packing paintings into boxes and storing bronze and marble sculptures into wooden crates and loading them into convoys of trucks that would ferry them to chateaux across the country.

Perched on a pedestal of wooden moving crates, Venus de Milo wears a harness of cords around her slim marble waist in one image.

Another of the Louvre's Greek masterpieces, the 2nd century B.C. Winged Victory of Samothrace, is shown entangled in a web of ropes and dangling from an oversized pulley. Another photo shows the a massive crate containing the marble statue being wheeled down a staircase on specially installed wooden planks.

"The principle was that the artwork had to be gotten away from combat zones and strategic centers," said the exhibition's curator, Guillaume Fonkenell, adding that the pieces weren't hidden from the occupying Nazi forces.

"The Germans were perfectly aware of the different places the artwork was being stored," he said. Most of it was kept at chateaux, whose owners volunteered to safeguard the pieces as a way of preventing their properties from being requisitioned by the Nazis, Fonkenell said.

The situation in Paris was vastly different than in other European capitals occupied by the Germans, like Warsaw or Prague, which saw treasures in their museums plundered.

Generally, the pieces remained sealed in their boxes, but curators worried about the conditions of the Mona Lisa and took the painting out of its box.

"It was stored in a bedroom so that there would always be someone with her," said Fonkenell. "There were people who slept with Mona Lisa in their bedroom."

Nearly all the Louvre's collection of paintings was evacuated from Paris. But harder-to-transport items, like fragile pieces and heavy sculptures, were removed only selectively.

Much of the remaining artwork was stored in the museum's basement during the war. One shot shows dozens of Roman statues of life-sized toga-draped men and women crowded together, as if they were posing for a group photo.

The most chilling images are the ones taken after the artwork's removal.

The Grande Galerie, stripped of its floor-to-ceiling paintings, stretches out in infinite ennui. Heavy shadows envelop the stately marble hallway where the Venus de Milo had presided.

A 1942 photo shows a gallery once dedicated to Rembrandt, dozens of gilded frames hanging, empty, from the walls. Inside the frames, the names of the paintings that once hung there were scrawled in chalk on the walls.

"It's strange for us to imagine, but there was not a single painting exhibited," said Fonkenell. "The Louvre without a painting, it's a little bizarre."

The museum remained open during much of the war, though only a few halls and just a fraction of the collection — mostly sculptures — was exposed.

Germans got in for free, but French citizens had to pay an entrance fee, Fonkenell said. Several images from 1940 show Nazi officers and soldiers visiting the museum.

The Louvre also served as a warehouse for artwork stolen from Jewish collectors. A 1943 image shows 170 canvases stacked against a wall, while another shows a hall cluttered with crates containing sculptures and other large pieces.

Some of the stolen paintings — those judged by a Nazi-appointed panel of "experts" to have little artistic or commercial value — were shredded and burned in the neighboring Tuileries Gardens in 1943, according to the exhibition's catalog.

After the war, many of the stolen pieces were restored to their rightful owners or their families. Works that went unclaimed were held by the French government and stored in museums pending their return. Some are still in French custody, Fonkenell said.

After the war, pieces removed from the Louvre trickled slowly back to the museum. Gas shortages and a lack of coal — used to heat the mammoth complex — slowed the process down, the catalog said.

It's the photos of artwork being restored to its old spot that are the exhibition's most moving. In a June, 1945 shot, two men carry Eugene Delacroix's iconic 1831 painting Liberty Leading the People, its bare-breasted heroine brandishing France's tricolor flag.

The expectation is almost palpable in a June, 1945 photo of the unveiling of the Mona Lisa. As a museum curator opens the box, her soulful eyes and a glimpse of her mysterious smile peek out from beneath layers of protective paper.

To report corrections and clarifications, contact Reader Editor Brent Jones. For publication consideration in the newspaper, send comments to letters@usatoday.com. Include name, phone number, city and state for verification. To view our corrections, go to corrections.usatoday.com.

Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more.